Static Magnetic Cloak without a Superconductor

Cloaking is very interesting, for magnetic fields as well as light, but standard approaches are held back by technical challenges. This work shows that a diamagnetic active-current boundary combined with a high-permeability magnetic shell can be precisely engineered to overcome the usual permeability and frequency-band limits, for a robust cloak covering the entire quasistatic frequency region, without using superconductors---no cryogenics required. These results provides an efficient way to circumvent the traditional limits of metamaterials and realize magnetic cloaks for ultralow frequencies, and could be generalized to yield other artificial magnetic systems as well.